The expression of eukaryotic DNA in E. coli will be analyzed employing a recombinant plasmids carrying the qa-2 gene (pVK88) of Neurospora crassa and the his3 (pKK1), his4 (pHis4) and ura3(yIP5) loci of Saccaromyces cervisiae. Employing partial restriction endonuclease digests, the entire qa gene cluster from N. crassa (a group of four contiguous genes) will be cloned into E. coli and analyzed. The 20-200-fold increase in the expression of the catabolic dehydroquinase observed in polynucleotide phosphorylase (pnp) deficient strains of E. coli will be studied both genetically and biochemically. Alterations in the level of transcription, stability of mRNA, and ribosome binding will be examined. The generality of the phenomenon will be tested with recombinant plasmids carrying yeast genes already known to be expressed in E. coli. Attempts will be made to determine if additional N. crassa and S. cervisiae genes can be cloned in high expressing strains which otherwise would not be expressed in E. coli. Similar cloning experiments will be carried out with nuclear DNA from Aspergillus nidulans and Euglena gracilis. Plasmids containing cDNA copies of genes from higher organisms will also be tested for functional expression in mutationally altered E. coli strains.